Atomically confined calcium in nitrogen-doped graphene as an efficient heterogeneous catalyst for hydrogen evolution

Jie Sun; Suchun Li; Qi Zhao; Cunping Huang; Qiang Wu; Wei Chen; Qunjie Xu; Weifeng Yao

doi:10.1016/j.isci.2021.102728

Atomically confined calcium in nitrogen-doped graphene as an efficient heterogeneous catalyst for hydrogen evolution

iScience. 2021 Jun 15;24(7):102728. doi: 10.1016/j.isci.2021.102728. eCollection 2021 Jul 23.

Authors

Jie Sun¹, Suchun Li², Qi Zhao^{1

3}, Cunping Huang⁴, Qiang Wu¹, Wei Chen², Qunjie Xu^{1

5

6}, Weifeng Yao^{1

5

6}

Affiliations

¹ Shanghai Key Laboratory of Materials Protection and Advanced Materials in Electric Power, College of Environmental & Chemical Engineering, Shanghai University of Electric Power, No.2588 Changyang Road, Yangpu District, Shanghai, 200090, PR China.
² Department of Physics and John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA.
³ Center of Super-Diamond and Advanced Films (COSDAF) and Department of Chemistry, City University of Hong Kong, Hong Kong SAR, 999077 P. R. China.
⁴ Aviation Fuels Research Laboratory, Federal Aviation Administration William J. Hughes Technical Center, Atlantic City International Airport, NJ 08405, USA.
⁵ Shanghai Institute of Pollution Control and Ecological Security, Shanghai 200090, PR China.
⁶ Shanghai Engineering Research Center of Heat-exchange System and Energy Saving, Shanghai University of Electric Power, Shanghai 200090, PR China.

Abstract

Calcium is one of the most abundant and cheapest elements on earth. However, due to the lack of d-orbitals for chemical adsorption, it is generally considered as a stoichiometric reagent with no catalytic activities in heterogeneous catalysis. In this research, we have revealed that atomically confined Ca in nitrogen-doped graphene (Ca₁-NG) can be an effective heterogeneous catalyst to boost both electrocatalytic and photocatalytic hydrogen evolution reactions (HER). Ca single atoms anchored in NG can efficiently enhance the HER performance due to the improvement of the interfacial charge transfer rate and suppression of the photo-generated charge recombination. Density functional theory calculations show that the high catalytic activity of Ca₁-NG results from the Ca single atoms in NG, which leads to multiple H adsorption configurations with favorable ΔG_H∗ values for HER. This research can be valuable for the designing of environmentally friendly, economical and efficient catalysts for renewable hydrogen production.

Keywords: catalysis; chemical engineering; electrochemistry.